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Bunny::Queue

DESCRIPTION:

Queues store and forward messages. Queues can be configured in the server or created at runtime. Queues must be attached to at least one exchange in order to receive messages from publishers.

Public Class Methods

new(client, name, opts = {}) click to toggle source
# File lib/bunny/queue08.rb, line 14
    def initialize(client, name, opts = {})
                  # check connection to server
                  raise Bunny::ConnectionError, 'Not connected to server' if client.status == :not_connected
                  
      @client = client
      @opts   = opts
@delivery_tag = nil
@subscription = nil

# Queues without a given name are named by the server and are generally
# bound to the process that created them.
if !name
  opts = {
    :passive => false,
    :durable => false,
    :exclusive => true,
    :auto_delete => true
  }.merge(opts)
end
  
                  # ignore the :nowait option if passed, otherwise program will hang waiting for a
                  # response that will not be sent by the server
                  opts.delete(:nowait)
                  
      client.send_frame(
        Qrack::Protocol::Queue::Declare.new({ :queue => name || '', :nowait => false }.merge(opts))
      )
  
method = client.next_method

                  client.check_response(method,        Qrack::Protocol::Queue::DeclareOk, "Error declaring queue #{name}")

@name = method.queue
                  client.queues[@name] = self
    end

Public Instance Methods

ack(opts={}) click to toggle source

DESCRIPTION:

Acknowledges one or more messages delivered via the Deliver or Get-Ok methods. The client can ask to confirm a single message or a set of messages up to and including a specific message.

OPTIONS:

  • :delivery_tag

  • :multiple => true or false (default) - If set to true, the delivery tag is treated as "up to and including", so that the client can acknowledge multiple messages with a single method. If set to false, the delivery tag refers to a single message. If the multiple field is true, and the delivery tag is zero, tells the server to acknowledge all outstanding messages.

# File lib/bunny/queue08.rb, line 67
            def ack(opts={})
                    # Set delivery tag
                    if delivery_tag.nil? and opts[:delivery_tag].nil?
                            raise Bunny::AcknowledgementError, "No delivery tag received"
                    else
                            self.delivery_tag = opts[:delivery_tag] if delivery_tag.nil?
                    end
                    
  client.send_frame(
    Qrack::Protocol::Basic::Ack.new({:delivery_tag => delivery_tag, :multiple => false}.merge(opts))
  )

                    # reset delivery tag
                    self.delivery_tag = nil
end
bind(exchange, opts = {}) click to toggle source

DESCRIPTION:

Binds a queue to an exchange. Until a queue is bound it will not receive any messages. Queues are bound to the direct exchange ” by default. If error occurs, a Bunny::ProtocolError is raised.

  • :key => 'routing key'* <tt>:key => 'routing_key' - Specifies the routing key for the binding. The routing key is used for routing messages depending on the exchange configuration.

  • :nowait => true or false (default) - Ignored by Bunny, always false.

RETURNS:

:bind_ok if successful.

# File lib/bunny/queue08.rb, line 100
def bind(exchange, opts = {})
  exchange           = exchange.respond_to?(:name) ? exchange.name : exchange

              # ignore the :nowait option if passed, otherwise program will hang waiting for a
              # response that will not be sent by the server
              opts.delete(:nowait)

  client.send_frame(
    Qrack::Protocol::Queue::Bind.new({ :queue => name,
                                                                                                                                    :exchange => exchange,
                                                                                                                                    :routing_key => opts.delete(:key),
                                                                                                                                    :nowait => false }.merge(opts))
  )
        
              method = client.next_method

              client.check_response(method,        Qrack::Protocol::Queue::BindOk,
                      "Error binding queue: #{name} to exchange: #{exchange}")

              # return message
              :bind_ok
end
delete(opts = {}) click to toggle source

DESCRIPTION:

Requests that a queue is deleted from broker/server. When a queue is deleted any pending messages are sent to a dead-letter queue if this is defined in the server configuration. Removes reference from queues if successful. If an error occurs raises Bunny::ProtocolError.

Options:

  • :if_unused => true or false (default) - If set to true, the server will only delete the queue if it has no consumers. If the queue has consumers the server does not delete it but raises a channel exception instead.

  • :if_empty => true or false (default) - If set to true, the server will only delete the queue if it has no messages. If the queue is not empty the server raises a channel exception.

  • :nowait => true or false (default) - Ignored by Bunny, always false.

Returns:

:delete_ok if successful

# File lib/bunny/queue08.rb, line 146
def delete(opts = {})
              # ignore the :nowait option if passed, otherwise program will hang waiting for a
              # response that will not be sent by the server
              opts.delete(:nowait)

  client.send_frame(
    Qrack::Protocol::Queue::Delete.new({ :queue => name, :nowait => false }.merge(opts))
  )
        
              method = client.next_method

              client.check_response(method,        Qrack::Protocol::Queue::DeleteOk, "Error deleting queue #{name}")

              client.queues.delete(name)

              # return confirmation
              :delete_ok
end
pop(opts = {}, &blk) click to toggle source

DESCRIPTION:

Gets a message from a queue in a synchronous way. If error occurs, raises Bunny::ProtocolError.

OPTIONS:

  • :ack => false (default) or true - If set to false, the server does not expect an acknowledgement message from the client. If set to true, the server expects an acknowledgement message from the client and will re-queue the message if it does not receive one within a time specified by the server.

RETURNS:

Hash {:header, :payload, :delivery_details}. :delivery_details is a hash {:consumer_tag, :delivery_tag, :redelivered, :exchange, :routing_key}.

If the queue is empty the returned hash will contain the values -

:header => nil
:payload => :queue_empty
:delivery_details => nil

N.B. If a block is provided then the hash will be passed into the block and the return value will be nil.

# File lib/bunny/queue08.rb, line 194
def pop(opts = {}, &blk)
              
              # do we want to have to provide an acknowledgement?
              ack = opts.delete(:ack)
              
  client.send_frame(
    Qrack::Protocol::Basic::Get.new({ :queue => name,
                                                                                                                               :consumer_tag => name,
                                                                                                                               :no_ack => !ack,
                                                                                                                               :nowait => true }.merge(opts))
  )
        
              method = client.next_method
              
              if method.is_a?(Qrack::Protocol::Basic::GetEmpty) then
                      queue_empty = true
              elsif        !method.is_a?(Qrack::Protocol::Basic::GetOk)
                      raise Bunny::ProtocolError, "Error getting message from queue #{name}"
              end
              
              if !queue_empty
                      # get delivery tag to use for acknowledge
                      self.delivery_tag = method.delivery_tag if ack
              
          header = client.next_payload
        
          # If maximum frame size is smaller than message payload body then message
                      # will have a message header and several message bodies
                      msg = ''
                      while msg.length < header.size
                              msg += client.next_payload
                      end
                      
                      msg_hash = {:header => header, :payload => msg, :delivery_details => method.arguments}
                      
              else
                      msg_hash = {:header => nil, :payload => :queue_empty, :delivery_details => nil}
              end
              
              # Pass message hash to block or return message hash
              blk ? blk.call(msg_hash) : msg_hash          
              
end
purge(opts = {}) click to toggle source

DESCRIPTION:

Removes all messages from a queue. It does not cancel consumers. Purged messages are deleted without any formal “undo” mechanism. If an error occurs raises Bunny::ProtocolError.

Options:

  • :nowait => true or false (default) - Ignored by Bunny, always false.

Returns:

:purge_ok if successful

# File lib/bunny/queue08.rb, line 254
      def purge(opts = {})
              # ignore the :nowait option if passed, otherwise program will hang waiting for a
              # response that will not be sent by the server
              opts.delete(:nowait)

  client.send_frame(
    Qrack::Protocol::Queue::Purge.new({ :queue => name, :nowait => false }.merge(opts))
  )
        
              method = client.next_method

              client.check_response(method,        Qrack::Protocol::Queue::PurgeOk, "Error purging queue #{name}")

              # return confirmation
              :purge_ok

end
status() click to toggle source

DESCRIPTION:

Returns hash {:message_count, :consumer_count}.

# File lib/bunny/queue08.rb, line 280
def status
  client.send_frame(
    Qrack::Protocol::Queue::Declare.new({ :queue => name, :passive => true })
  )
  method = client.next_method
  {:message_count => method.message_count, :consumer_count => method.consumer_count}
end
subscribe(opts = {}, &blk) click to toggle source
# File lib/bunny/queue08.rb, line 289
def subscribe(opts = {}, &blk)
                    # Create subscription
                    s = Bunny::Subscription.new(client, self, opts)
                    s.start(&blk)
                    
                    # Reset when subscription finished
                    @subscription = nil
            end
unbind(exchange, opts = {}) click to toggle source

DESCRIPTION:

Removes a queue binding from an exchange. If error occurs, a Bunny::ProtocolError is raised.

OPTIONS:

  • :key => 'routing key'* <tt>:key => 'routing_key' - Specifies the routing key for the binding.

  • :nowait => true or false (default) - Ignored by Bunny, always false.

RETURNS:

:unbind_ok if successful.

# File lib/bunny/queue08.rb, line 358
def unbind(exchange, opts = {})
  exchange = exchange.respond_to?(:name) ? exchange.name : exchange
        
              # ignore the :nowait option if passed, otherwise program will hang waiting for a
              # response that will not be sent by the server
              opts.delete(:nowait)

  client.send_frame(
    Qrack::Protocol::Queue::Unbind.new({ :queue => name,
                                                                                                                                            :exchange => exchange,
                                                                                                                                            :routing_key => opts.delete(:key),
                                                                                                                                            :nowait => false }.merge(opts)
    )
  )
        
              method = client.next_method

              client.check_response(method,        Qrack::Protocol::Queue::UnbindOk, "Error unbinding queue #{name}")
                      
              # return message
              :unbind_ok
end
unsubscribe(opts = {}) click to toggle source

DESCRIPTION:

Cancels a consumer. This does not affect already delivered messages, but it does mean the server will not send any more messages for that consumer.

OPTIONS:

  • :consumer_tag => 'tag' - Specifies the identifier for the consumer.

  • :nowait => true or false (default) - Ignored by Bunny, always false.

Returns:

:unsubscribe_ok if successful

# File lib/bunny/queue08.rb, line 316
            def unsubscribe(opts = {})
                    # Default consumer_tag from subscription if not passed in
                    consumer_tag = subscription ? subscription.consumer_tag : opts[:consumer_tag]
                    
                    # Must have consumer tag to tell server what to unsubscribe
                    raise Bunny::UnsubscribeError,
                            "No consumer tag received" if !consumer_tag
                    
  # Cancel consumer
  client.send_frame( Qrack::Protocol::Basic::Cancel.new(:consumer_tag => consumer_tag,
                                                                                                                                                                                                                                            :nowait => false))
                                                                                                                                                                                                                                            
                    method = client.next_method

                    client.check_response(method,        Qrack::Protocol::Basic::CancelOk,
                            "Error unsubscribing from queue #{name}")

                    # Reset subscription
                    @subscription = nil
                            
                    # Return confirmation
                    :unsubscribe_ok
                    
end

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